On August 9th, 2022, the U.S. Food and Drug Administration issued an emergency use authorization (EUA) for the JYNNEOS vaccine. Here is what you need to know about the monkeypox vaccine emergency use authorization. 

JYNNEOS Vaccine Authorization Details 

This authorization allows healthcare providers to administer the vaccine by intradermal injection for high risk individuals that are 18 years of age or older. By allowing this vaccine to be administered intradermally, it will increase the total number of doses available by up to five-fold. The EUA also allows for the vaccine to be administered to individuals younger than 18 years of age who are determined to be at high risk of monkeypox infection. In this under 18 years old group, the JYNNEOS vaccine is administered subcutaneously.

Background of the JYNNEOS Vaccine

JYNNEOS, produced by Denmark’s Bavarian Nordic, was approved in 2019 for the prevention of smallpox and monkeypox disease in adults at high risk of contracting the disease that were 18 years of age and older. In this original indication, the JYNNEOS vaccine is administered as two doses from a single use vial, subcutaneously, 28 days apart. A person is considered protected 14 days after the second dose.

For Monkeypox prevention, the EUA now allows for a smaller amount of the subcutaneous dose to be administered intradermally. The timing of the vaccine will remain the same, with two doses given 28 days apart. This dosing method is based on a clinical study from 2015 that compared intradermal dosing to subcutaneous for this vaccine.

JYNNEOS Vaccine Contraindications and Precautions

The JYNNEOS vaccine is contraindicated and not recommended for individuals who had a severe allergic reaction to a prior dose of JYNNEOS. 

Additionally, the JYNNEOS vaccine contains small amounts of gentamicin and ciprofloxacin and is produced using chicken embryo fibroblast cells. Due to these components extra precautions are recommended prior to receiving the vaccine and post-vaccination surveillance is recommended for individuals with a history of a severe allergic reaction to gentamicin or ciprofloxacin. Precautions should also be taken for people who have a history of severe allergic reaction to chicken or egg protein and are currently avoiding exposure to all chicken or egg products. Lastly, precautions should be taken for people experiencing moderate or severe acute illness, with or without fever on the day of vaccination – in this case, it is recommended to delay the vaccine until the illness resolves.

JYNNEOS Vaccine Side Effects

Possible side effects from the JYNNEOS vaccine include injection site pain, swelling, itching, tiredness, headache, nausea, chills, and muscle aches. Patients receiving the intradermal administration route may also experience prolonged hardening of the skin or redness of the skin at the injection site. Most side effects will resolve on their own. 

Preventative Measures and Closing Points

In conjunction with the vaccine, it is important to continue to counsel patients on preventative measures that can be taken to avoid Monkeypox infection. Individuals can prevent Monkeypox infection by avoiding close contact, including skin-to-skin and intimate contact, with someone who has the disease. It can also be prevented by avoiding prolonged exposure to respiratory secretions, this includes face-to-face contact with someone currently infected. According to the CDC, “A person is considered to be infectious until there is full healing of the rash with formation of a fresh layer of skin.” 

Educating our community on preventative measures is key as we navigate the unknown territory of the vaccine effectiveness in this outbreak.